1. Field of the Invention
The present invention relates to a binding device, and in particular, to a binding device used as, for example, a ring binder or a file.
2. Description of the Related Art
An example of conventional binding devices is disclosed in, for example, Japanese Patent Laid-Open Publication No. 2004-255835 (Patent Document 1). In the binding device disclosed in this publication, an operating member having binding rings attached thereto is secured by holding projections provided in a holding member. Furthermore, binding ring-engaging portions on respective free ends of ring halves defining each of the binding rings are engaged with each other, whereby each of the annular binding rings is provided, and the transverse cross-sectional shape of the binding rings is a substantially ellipsoidal shape.
In the above conventional binding device, the operating member is secured by the holding projections and provided in the holding member. However, it is very difficult to provide the holding projections to the holding member, and therefore the manufacturing of the entire binding device is complicated and requires much effort. Furthermore, when the binding rings in a closed state are opened, the operating member often does not operate smoothly.